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jbeale

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  1. jbeale

    OpenSCAD images do not match my model

    Colors would be nice to have, but it is secondary. The more important problem is that most of the cylinders were rendered incorrectly, or not at all.
  2. It is very nice that you are making renderings from OpenSCAD files uploaded. However I wonder what version of OpenSCAD you are using, because it doesn't match my model. Compare what I see: with what your software rendered, below. Colors don't translate, OK; but I see the screw heads are missing. Also, the cylinders modelling the caps and toroid on the PCB have the wrong (much too small) diameter. The cylindrical screw bosses in the case top & bottom are completely gone. I am using OpenSCAD version 2014.10.02 (beta) but this file also renders properly in OpenScad version 2014.03 .
  3. Maybe OT since I have a UM2 which came with a glass bed already. Anyway, after using a thin receipt slip paper for levelling, and setting first layer to 0.1 mm in Cura, and using a vanishingly-thin layer of glue stick for PLA adhesion, the bottom surface quality looks quite good to me. Practically like an injection-molded part: https://www.youmagine.com/designs/28byj-48-mounting-bracket My only mod is a fan shroud which I think improved overhang performance slightly, but I think careful extrusion temperature and speed adjustment is the more important factor.
  4. jbeale

    Is there some way (hack) to print at 270C?

    If you are going to machine something, the isolator might be a good application for a machinable ceramic like Macor: http://en.wikipedia.org/wiki/Macor It is stable up to 800 °C and being a glass ceramic it has much lower thermal conductivity than metal: Aluminum: 205 W/(m.K) Macor: 1.46 W/(m.K) Macor is a somewhat exotic and expensive material, but you only need a small piece.
  5. I am playing around with some "deep groove" ball bearings. I have read that "Deep groove ball bearings mainly take radial load as well as moderate axial load." But what does that mean exactly? For example, one particular bearing (6203Z, OD=40mm) has a spec for static (4.8 kN) and dynamic (9.55 kN) loads but I think that is radial only. Since there is no spec number provided for axial load, is there some rule of thumb for "moderate" like 1/10 or 1/100 of radial load, or should I assume it really cannot handle any axial force at all? Pushing in on it just by hand, it feels pretty solid, though. This size bearing is used in some machine tools, motorcycle crankcase, etc. http://www.amazon.com/Bearing-6203Z-17x40x12-Single-Shielded/dp/B002BBAWUE EDIT: Ok, maybe this is my answer; 1/2 to 1/4 of rated static load Co:
  6. jbeale

    Build Plate Wire Smoke

    Certainly something to consider. I believe the printer that caught fire was enclosed on 4 sides with acrylic. Some people are doing that to stabilize buildplate temperatures, but like many plastics, acrylic is flammable. Plexiglas (a brand of PMMA or poly(methyl methacrylate), a form of acrylic) starts softening around 102 C and ignites at 300 C, according to http://www.plexiglas.net/product/plexiglas/en/about/faq/Pages/fire-behavior.aspx PLA filament self-ignites at 388 C according to http://en.wikipedia.org/wiki/Dust_explosion Plastic shards and dust can build up whenever the extruder grinds the filament. I guess the plastic would melt before it burns so it wouldn't be dust anymore, but still seems an argument in favor of the UM design, separating the feeder from the hot end. Some people put a 3D printer in the garage or workshop, where smoke detectors should not be used because car exhaust or dust from power tools can set them off. You can however use a heat alarm mounted somewhere near the ceiling, which triggers both at high temperature, and high rate-of-rise of temperature. Amazon has them for about $25. Just on general principles, having a fire extinguisher on hand is not a bad idea either.
  7. jbeale

    Build Plate Wire Smoke

    And by the way, don't assume that a 3D printer will not cause a fire, because one already has. The house was lost, along with a pet. http://www.soliforum.com/topic/6608/beware-your-3d-printer-they-can-cause-fires/
  8. jbeale

    Dimensions not matching files

    With my UM2 printer, I oversize holes by 0.2 mm in diameter and they generally come out very close to correct. Print head 225 C, bed 60 C and then 45C after the first few layers, speed 20 mm/sec, "Ultimaker Blue" PLA filament. The very first layer is set to 0.3mm thick and gets squished out more, so I do have to ream out holes but it's mostly just that first layer edge.
  9. jbeale

    Build Plate Wire Smoke

    If something is smoking, that's obviously a safety hazard. I often do long and unattended runs on my printer, sitting in a room with no smoke detector but I'm going to change that right away! Meanwhile, a photo of what bad connector wiring looks like, would help. I assume the clips are not fully inserted in the connector, so the wires can short out as the cable flexes when the platform moves up and down the Z axis? Is there no overcurrent fault protection on the heater? Or, given that the heater power seems to be 150 watts or so, maybe just the normal current when concentrated in a small area by wires touching, causes the damage.
  10. jbeale

    NASA releases printable models

    Neat collection! I had a look at the Kepler spacecraft- looks tricky to print since there isn't one flat surface to use as a base.The solar panels are flat, but many fine details protrude beyond those planes. Cut in half and assemble it, I guess.
  11. It would certainly be good to have smart filters that show you only the "good stuff", although that depends on your interests... For example, I am working more often with functional mechanical parts as opposed to art and I am mostly interested in models with OpenSCAD source provided, because I usually want to change some dimensions to suit the project at hand, and I don't have access to SolidWorks etc.
  12. I think YouMagine is improving in user base size. My most popular design that is on both sites shows a 3:1 ratio of downloads, and 7:1 ratio of like/favorites, when comparing Thingiverse:YouMagine. https://www.youmagine.com/designs/universal-joint-with-bearings (80 D/L, 10 favorites) http://www.thingiverse.com/thing:392828 (264 D/L, 70 likes) Maybe not directly comparable, but certainly different from the 100:1 ratio that IRobertI reported back in January. If I hadn't posted it on Thingiverse, I wouldn't have been able to proudly reply there when a comment praised the surface finish in my photo and asked me what printer I used. :smile: Note: this forum has an annoying bug that HTML links get merged together with any following text on the same line, and mangled in the process. So any link must be the last thing on a line. It would be nice to see that fixed!
  13. Excellent guide, by far the most useful thing I have come across yet in these forums. Every UM owner should have this link.
  14. I have heard that not everything can color PLA filament well, but just FYI the first thing I tried worked OK: metal layout dye. I didn't use paint, because I didn't want to increase the diameter of the part. I tried it on an 8 mm shaft I printed and the fit remains the same, so I think the dimension did not change more than 0.1 mm anyway. This fluid comes in only a few colors, most frequently blue or red. I tried some blue on the light-blue PLA that came with my UM2. It turned it a nice dark blue-purple. The color was not entirely even since I brushed it on, but that might be improved with some more care. Be aware the smell is somewhat annoying, although not awful. The label says it contains Ethanol, Butyl Acetate, Isopropanol, Nitrocellulose, 1-Butanol, Propyl Acetate and to use with adequate ventilation. The exact product I used was Dykem 80300 BLUE from http://www.amazon.com/gp/product/B0018ACR6G/ and they also have it in red color. Another brand is Beechem who have blue, red, green, black, purple, yellow and orange. http://www.shelbygemfactory.com/KelleyBeechem-Labs_ep_34-1.html
  15. jbeale

    Ugly Image Sizes

    As far as I can tell, YouMagine is first cropping my original rectangular image into a square in the upload preview window, loosing the right and left edges. Then, after confirming the upload, the main page crops the image again into a smaller rectangle, this time removing some from the top and bottom, so it has been double-cropped by the time it appears on the user page. I don't think that is what you want or intended. I had to first swell my image with a 130% blank border in photoshop before uploading, to get around this. Not a great situation, so a fix would be welcome.
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